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Unified Diff: lib/Target/X86/X86NaClRewritePass.cpp

Issue 939073008: Rebased PNaCl localmods in LLVM to 223109 (Closed)
Patch Set: undo localmod Created 5 years, 10 months ago
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Index: lib/Target/X86/X86NaClRewritePass.cpp
diff --git a/lib/Target/X86/X86NaClRewritePass.cpp b/lib/Target/X86/X86NaClRewritePass.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..004ed16336aa76c44d682e835fa2d44effad9665
--- /dev/null
+++ b/lib/Target/X86/X86NaClRewritePass.cpp
@@ -0,0 +1,752 @@
+//=== X86NaClRewritePAss.cpp - Rewrite instructions for NaCl SFI --*- C++ -*-=//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains a pass that ensures stores and loads and stack/frame
+// pointer addresses are within the NaCl sandbox (for x86-64).
+// It also ensures that indirect control flow follows NaCl requirments.
+//
+// The other major portion of rewriting for NaCl is done in X86InstrNaCl.cpp,
+// which is responsible for expanding the NaCl-specific operations introduced
+// here and also the intrinsic functions to support setjmp, etc.
+//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "x86-sandboxing"
+
+#include "X86.h"
+#include "X86InstrInfo.h"
+#include "X86NaClDecls.h"
+#include "X86Subtarget.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineJumpTableInfo.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/FormattedStream.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/CommandLine.h"
+
+using namespace llvm;
+
+cl::opt<bool> FlagRestrictR15("sfi-restrict-r15",
+ cl::desc("Restrict use of %r15. This flag can"
+ " be turned off for the zero-based"
+ " sandbox model."),
+ cl::init(true));
+
+namespace {
+ class X86NaClRewritePass : public MachineFunctionPass {
+ public:
+ static char ID;
+ X86NaClRewritePass() : MachineFunctionPass(ID) {}
+
+ virtual bool runOnMachineFunction(MachineFunction &Fn);
+
+ virtual const char *getPassName() const {
+ return "NaCl Rewrites";
+ }
+
+ private:
+
+ const TargetMachine *TM;
+ const TargetInstrInfo *TII;
+ const TargetRegisterInfo *TRI;
+ const X86Subtarget *Subtarget;
+ bool Is64Bit;
+
+ bool runOnMachineBasicBlock(MachineBasicBlock &MBB);
+
+ void TraceLog(const char *func,
+ const MachineBasicBlock &MBB,
+ const MachineBasicBlock::iterator MBBI) const;
+
+ bool ApplyRewrites(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator MBBI);
+ bool ApplyStackSFI(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator MBBI);
+
+ bool ApplyMemorySFI(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator MBBI);
+
+ bool ApplyFrameSFI(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator MBBI);
+
+ bool ApplyControlSFI(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator MBBI);
+
+ bool AlignJumpTableTargets(MachineFunction &MF);
+ };
+
+ char X86NaClRewritePass::ID = 0;
+
+}
+
+static void DumpInstructionVerbose(const MachineInstr &MI) {
+ DEBUG({
+ dbgs() << MI;
+ dbgs() << MI.getNumOperands() << " operands:" << "\n";
+ for (unsigned i = 0; i < MI.getNumOperands(); ++i) {
+ const MachineOperand& op = MI.getOperand(i);
+ dbgs() << " " << i << "(" << (unsigned)op.getType() << "):" << op
+ << "\n";
+ }
+ dbgs() << "\n";
+ });
+}
+
+static bool IsPushPop(MachineInstr &MI) {
+ const unsigned Opcode = MI.getOpcode();
+ switch (Opcode) {
+ default:
+ return false;
+ case X86::PUSH64r:
+ case X86::POP64r:
+ return true;
+ }
+}
+
+static bool IsStore(MachineInstr &MI) {
+ return MI.mayStore();
+}
+
+static bool IsLoad(MachineInstr &MI) {
+ return MI.mayLoad();
+}
+
+static bool IsFrameChange(MachineInstr &MI, const TargetRegisterInfo *TRI) {
+ return MI.modifiesRegister(X86::EBP, TRI);
+}
+
+static bool IsStackChange(MachineInstr &MI, const TargetRegisterInfo *TRI) {
+ return MI.modifiesRegister(X86::ESP, TRI);
+}
+
+static bool HasControlFlow(const MachineInstr &MI) {
+ return MI.getDesc().isBranch() ||
+ MI.getDesc().isCall() ||
+ MI.getDesc().isReturn() ||
+ MI.getDesc().isTerminator() ||
+ MI.getDesc().isBarrier();
+}
+
+static bool IsDirectBranch(const MachineInstr &MI) {
+ return MI.getDesc().isBranch() &&
+ !MI.getDesc().isIndirectBranch();
+}
+
+static bool IsRegAbsolute(unsigned Reg) {
+ const bool RestrictR15 = FlagRestrictR15;
+ assert(FlagUseZeroBasedSandbox || RestrictR15);
+ return (Reg == X86::RSP || Reg == X86::RBP ||
+ (Reg == X86::R15 && RestrictR15));
+}
+
+static bool FindMemoryOperand(const MachineInstr &MI,
+ SmallVectorImpl<unsigned>* indices) {
+ int NumFound = 0;
+ for (unsigned i = 0; i < MI.getNumOperands(); ) {
+ if (isMem(&MI, i)) {
+ NumFound++;
+ indices->push_back(i);
+ i += X86::AddrNumOperands;
+ } else {
+ i++;
+ }
+ }
+
+ // Intrinsics and other functions can have mayLoad and mayStore to reflect
+ // the side effects of those functions. This function is used to find
+ // explicit memory references in the instruction, of which there are none.
+ if (NumFound == 0)
+ return false;
+
+ return true;
+}
+
+static unsigned PromoteRegTo64(unsigned RegIn) {
+ if (RegIn == 0)
+ return 0;
+ unsigned RegOut = getX86SubSuperRegister(RegIn, MVT::i64, false);
+ assert(RegOut != 0);
+ return RegOut;
+}
+
+static unsigned DemoteRegTo32(unsigned RegIn) {
+ if (RegIn == 0)
+ return 0;
+ unsigned RegOut = getX86SubSuperRegister(RegIn, MVT::i32, false);
+ assert(RegOut != 0);
+ return RegOut;
+}
+
+
+//
+// True if this MI restores RSP from RBP with a slight adjustment offset.
+//
+static bool MatchesSPAdj(const MachineInstr &MI) {
+ assert (MI.getOpcode() == X86::LEA64r && "Call to MatchesSPAdj w/ non LEA");
+ const MachineOperand &DestReg = MI.getOperand(0);
+ const MachineOperand &BaseReg = MI.getOperand(1);
+ const MachineOperand &Scale = MI.getOperand(2);
+ const MachineOperand &IndexReg = MI.getOperand(3);
+ const MachineOperand &Offset = MI.getOperand(4);
+ return (DestReg.isReg() && DestReg.getReg() == X86::RSP &&
+ BaseReg.isReg() && BaseReg.getReg() == X86::RBP &&
+ Scale.getImm() == 1 &&
+ IndexReg.isReg() && IndexReg.getReg() == 0 &&
+ Offset.isImm());
+}
+
+void
+X86NaClRewritePass::TraceLog(const char *func,
+ const MachineBasicBlock &MBB,
+ const MachineBasicBlock::iterator MBBI) const {
+ DEBUG(dbgs() << "@" << func
+ << "(" << MBB.getName() << ", " << (*MBBI) << ")\n");
+}
+
+bool X86NaClRewritePass::ApplyStackSFI(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator MBBI) {
+ TraceLog("ApplyStackSFI", MBB, MBBI);
+ assert(Is64Bit);
+ MachineInstr &MI = *MBBI;
+
+ if (!IsStackChange(MI, TRI))
+ return false;
+
+ if (IsPushPop(MI))
+ return false;
+
+ if (MI.getDesc().isCall())
+ return false;
+
+ unsigned Opc = MI.getOpcode();
+ DebugLoc DL = MI.getDebugLoc();
+ unsigned DestReg = MI.getOperand(0).getReg();
+ assert(DestReg == X86::ESP || DestReg == X86::RSP);
+
+ unsigned NewOpc = 0;
+ switch (Opc) {
+ case X86::ADD64ri8 : NewOpc = X86::NACL_ASPi8; break;
+ case X86::ADD64ri32: NewOpc = X86::NACL_ASPi32; break;
+ case X86::SUB64ri8 : NewOpc = X86::NACL_SSPi8; break;
+ case X86::SUB64ri32: NewOpc = X86::NACL_SSPi32; break;
+ case X86::AND64ri8 : NewOpc = X86::NACL_ANDSPi8; break;
+ case X86::AND64ri32: NewOpc = X86::NACL_ANDSPi32; break;
+ }
+ if (NewOpc) {
+ BuildMI(MBB, MBBI, DL, TII->get(NewOpc))
+ .addImm(MI.getOperand(2).getImm())
+ .addReg(FlagUseZeroBasedSandbox ? 0 : X86::R15);
+ MI.eraseFromParent();
+ return true;
+ }
+
+ // Promote "MOV ESP, EBP" to a 64-bit move
+ if (Opc == X86::MOV32rr && MI.getOperand(1).getReg() == X86::EBP) {
+ MI.getOperand(0).setReg(X86::RSP);
+ MI.getOperand(1).setReg(X86::RBP);
+ MI.setDesc(TII->get(X86::MOV64rr));
+ Opc = X86::MOV64rr;
+ }
+
+ // "MOV RBP, RSP" is already safe
+ if (Opc == X86::MOV64rr && MI.getOperand(1).getReg() == X86::RBP) {
+ return true;
+ }
+
+ // Promote 32-bit lea to 64-bit lea (does this ever happen?)
+ assert(Opc != X86::LEA32r && "Invalid opcode in 64-bit mode!");
+ if (Opc == X86::LEA64_32r) {
+ unsigned DestReg = MI.getOperand(0).getReg();
+ unsigned BaseReg = MI.getOperand(1).getReg();
+ unsigned Scale = MI.getOperand(2).getImm();
+ unsigned IndexReg = MI.getOperand(3).getReg();
+ assert(DestReg == X86::ESP);
+ assert(Scale == 1);
+ assert(BaseReg == X86::EBP);
+ assert(IndexReg == 0);
+ MI.getOperand(0).setReg(X86::RSP);
+ MI.getOperand(1).setReg(X86::RBP);
+ MI.setDesc(TII->get(X86::LEA64r));
+ Opc = X86::LEA64r;
+ }
+
+ if (Opc == X86::LEA64r && MatchesSPAdj(MI)) {
+ const MachineOperand &Offset = MI.getOperand(4);
+ BuildMI(MBB, MBBI, DL, TII->get(X86::NACL_SPADJi32))
+ .addImm(Offset.getImm())
+ .addReg(FlagUseZeroBasedSandbox ? 0 : X86::R15);
+ MI.eraseFromParent();
+ return true;
+ }
+
+ if (Opc == X86::MOV32rr || Opc == X86::MOV64rr) {
+ BuildMI(MBB, MBBI, DL, TII->get(X86::NACL_RESTSPr))
+ .addReg(DemoteRegTo32(MI.getOperand(1).getReg()))
+ .addReg(FlagUseZeroBasedSandbox ? 0 : X86::R15);
+ MI.eraseFromParent();
+ return true;
+ }
+
+ if (Opc == X86::MOV32rm) {
+ BuildMI(MBB, MBBI, DL, TII->get(X86::NACL_RESTSPm))
+ .addOperand(MI.getOperand(1)) // Base
+ .addOperand(MI.getOperand(2)) // Scale
+ .addOperand(MI.getOperand(3)) // Index
+ .addOperand(MI.getOperand(4)) // Offset
+ .addOperand(MI.getOperand(5)) // Segment
+ .addReg(FlagUseZeroBasedSandbox ? 0 : X86::R15);
+ MI.eraseFromParent();
+ return true;
+ }
+
+ DEBUG(DumpInstructionVerbose(MI));
+ llvm_unreachable("Unhandled Stack SFI");
+}
+
+bool X86NaClRewritePass::ApplyFrameSFI(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator MBBI) {
+ TraceLog("ApplyFrameSFI", MBB, MBBI);
+ assert(Is64Bit);
+ MachineInstr &MI = *MBBI;
+
+ if (!IsFrameChange(MI, TRI))
+ return false;
+
+ unsigned Opc = MI.getOpcode();
+ DebugLoc DL = MI.getDebugLoc();
+
+ // Handle moves to RBP
+ if (Opc == X86::MOV64rr) {
+ assert(MI.getOperand(0).getReg() == X86::RBP);
+ unsigned SrcReg = MI.getOperand(1).getReg();
+
+ // MOV RBP, RSP is already safe
+ if (SrcReg == X86::RSP)
+ return false;
+
+ // Rewrite: mov %rbp, %rX
+ // To: naclrestbp %eX, %rZP
+ BuildMI(MBB, MBBI, DL, TII->get(X86::NACL_RESTBPr))
+ .addReg(DemoteRegTo32(SrcReg))
+ .addReg(FlagUseZeroBasedSandbox ? 0 : X86::R15); // rZP
+ MI.eraseFromParent();
+ return true;
+ }
+
+ // Handle memory moves to RBP
+ if (Opc == X86::MOV64rm) {
+ assert(MI.getOperand(0).getReg() == X86::RBP);
+
+ // Zero-based sandbox model uses address clipping
+ if (FlagUseZeroBasedSandbox)
+ return false;
+
+ // Rewrite: mov %rbp, (...)
+ // To: naclrestbp (...), %rZP
+ BuildMI(MBB, MBBI, DL, TII->get(X86::NACL_RESTBPm))
+ .addOperand(MI.getOperand(1)) // Base
+ .addOperand(MI.getOperand(2)) // Scale
+ .addOperand(MI.getOperand(3)) // Index
+ .addOperand(MI.getOperand(4)) // Offset
+ .addOperand(MI.getOperand(5)) // Segment
+ .addReg(FlagUseZeroBasedSandbox ? 0 : X86::R15); // rZP
+ MI.eraseFromParent();
+ return true;
+ }
+
+ // Popping onto RBP
+ // Rewrite to:
+ // naclrestbp (%rsp), %rZP
+ // naclasp $8, %rZP
+ //
+ // TODO(pdox): Consider rewriting to this instead:
+ // .bundle_lock
+ // pop %rbp
+ // mov %ebp,%ebp
+ // add %rZP, %rbp
+ // .bundle_unlock
+ if (Opc == X86::POP64r) {
+ assert(MI.getOperand(0).getReg() == X86::RBP);
+
+ BuildMI(MBB, MBBI, DL, TII->get(X86::NACL_RESTBPm))
+ .addReg(X86::RSP) // Base
+ .addImm(1) // Scale
+ .addReg(0) // Index
+ .addImm(0) // Offset
+ .addReg(0) // Segment
+ .addReg(FlagUseZeroBasedSandbox ? 0 : X86::R15); // rZP
+
+ BuildMI(MBB, MBBI, DL, TII->get(X86::NACL_ASPi8))
+ .addImm(8)
+ .addReg(FlagUseZeroBasedSandbox ? 0 : X86::R15);
+
+ MI.eraseFromParent();
+ return true;
+ }
+
+ DEBUG(DumpInstructionVerbose(MI));
+ llvm_unreachable("Unhandled Frame SFI");
+}
+
+bool X86NaClRewritePass::ApplyControlSFI(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator MBBI) {
+ const bool HideSandboxBase = (FlagHideSandboxBase &&
+ Is64Bit && !FlagUseZeroBasedSandbox);
+ TraceLog("ApplyControlSFI", MBB, MBBI);
+ MachineInstr &MI = *MBBI;
+
+ if (!HasControlFlow(MI))
+ return false;
+
+ // Direct branches are OK
+ if (IsDirectBranch(MI))
+ return false;
+
+ DebugLoc DL = MI.getDebugLoc();
+ unsigned Opc = MI.getOpcode();
+
+ // Rewrite indirect jump/call instructions
+ unsigned NewOpc = 0;
+ switch (Opc) {
+ // 32-bit
+ case X86::JMP32r : NewOpc = X86::NACL_JMP32r; break;
+ case X86::TAILJMPr : NewOpc = X86::NACL_JMP32r; break;
+ case X86::CALL32r : NewOpc = X86::NACL_CALL32r; break;
+ // 64-bit
+ case X86::NACL_CG_JMP64r : NewOpc = X86::NACL_JMP64r; break;
+ case X86::CALL64r : NewOpc = X86::NACL_CALL64r; break;
+ case X86::TAILJMPr64 : NewOpc = X86::NACL_JMP64r; break;
+ }
+ if (NewOpc) {
+ unsigned TargetReg = MI.getOperand(0).getReg();
+ if (Is64Bit) {
+ // CALL64r, etc. take a 64-bit register as a target. However, NaCl gas
+ // expects naclcall/nacljmp pseudos to have 32-bit regs as targets
+ // so NACL_CALL64r and NACL_JMP64r stick with that as well.
+ // Demote any 64-bit register to 32-bit to match the expectations.
+ TargetReg = DemoteRegTo32(TargetReg);
+ }
+ MachineInstrBuilder NewMI =
+ BuildMI(MBB, MBBI, DL, TII->get(NewOpc))
+ .addReg(TargetReg);
+ if (Is64Bit) {
+ NewMI.addReg(FlagUseZeroBasedSandbox ? 0 : X86::R15);
+ }
+ MI.eraseFromParent();
+ return true;
+ }
+
+ // EH_RETURN has a single argment which is not actually used directly.
+ // The argument gives the location where to reposition the stack pointer
+ // before returning. EmitPrologue takes care of that repositioning.
+ // So EH_RETURN just ultimately emits a plain "ret".
+ // RETI returns and pops some number of bytes from the stack.
+ if (Opc == X86::RETL || Opc == X86::RETQ ||
+ Opc == X86::EH_RETURN || Opc == X86::EH_RETURN64 ||
+ Opc == X86::RETIL || Opc == X86::RETIQ) {
+ // To maintain compatibility with nacl-as, for now we don't emit naclret.
+ // MI.setDesc(TII->get(Is64Bit ? X86::NACL_RET64 : X86::NACL_RET32));
+ //
+ // For NaCl64 returns, follow the convention of using r11 to hold
+ // the target of an indirect jump to avoid potentially leaking the
+ // sandbox base address.
+ unsigned RegTarget;
+ if (Is64Bit) {
+ RegTarget = (HideSandboxBase ? X86::R11 : X86::RCX);
+ BuildMI(MBB, MBBI, DL, TII->get(X86::POP64r), RegTarget);
+ if (Opc == X86::RETIL || Opc == X86::RETIQ) {
+ BuildMI(MBB, MBBI, DL, TII->get(X86::NACL_ASPi32))
+ .addOperand(MI.getOperand(0))
+ .addReg(FlagUseZeroBasedSandbox ? 0 : X86::R15);
+ }
+
+ BuildMI(MBB, MBBI, DL, TII->get(X86::NACL_JMP64r))
+ .addReg(getX86SubSuperRegister(RegTarget, MVT::i32, false))
+ .addReg(FlagUseZeroBasedSandbox ? 0 : X86::R15);
+ } else {
+ RegTarget = X86::ECX;
+ BuildMI(MBB, MBBI, DL, TII->get(X86::POP32r), RegTarget);
+ if (Opc == X86::RETIL || Opc == X86::RETIQ) {
+ BuildMI(MBB, MBBI, DL, TII->get(X86::ADD32ri), X86::ESP)
+ .addReg(X86::ESP)
+ .addOperand(MI.getOperand(0));
+ }
+ BuildMI(MBB, MBBI, DL, TII->get(X86::NACL_JMP32r))
+ .addReg(RegTarget);
+ }
+ MI.eraseFromParent();
+ return true;
+ }
+
+ // Traps are OK (but are considered to have control flow
+ // being a terminator like RET).
+ if (Opc == X86::TRAP)
+ return false;
+
+ DEBUG(DumpInstructionVerbose(MI));
+ llvm_unreachable("Unhandled Control SFI");
+}
+
+//
+// Sandboxes loads and stores (64-bit only)
+//
+bool X86NaClRewritePass::ApplyMemorySFI(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator MBBI) {
+ TraceLog("ApplyMemorySFI", MBB, MBBI);
+ assert(Is64Bit);
+ MachineInstr &MI = *MBBI;
+
+ if (!IsLoad(MI) && !IsStore(MI))
+ return false;
+
+ if (IsPushPop(MI))
+ return false;
+
+ SmallVector<unsigned, 2> MemOps;
+ if (!FindMemoryOperand(MI, &MemOps))
+ return false;
+ bool Modified = false;
+ for (unsigned MemOp : MemOps) {
+ MachineOperand &BaseReg = MI.getOperand(MemOp + 0);
+ MachineOperand &Scale = MI.getOperand(MemOp + 1);
+ MachineOperand &IndexReg = MI.getOperand(MemOp + 2);
+ //MachineOperand &Disp = MI.getOperand(MemOp + 3);
+ MachineOperand &SegmentReg = MI.getOperand(MemOp + 4);
+
+ // RIP-relative addressing is safe.
+ if (BaseReg.getReg() == X86::RIP)
+ continue;
+
+ // Make sure the base and index are 64-bit registers.
+ IndexReg.setReg(PromoteRegTo64(IndexReg.getReg()));
+ BaseReg.setReg(PromoteRegTo64(BaseReg.getReg()));
+ assert(IndexReg.getSubReg() == 0);
+ assert(BaseReg.getSubReg() == 0);
+
+ bool AbsoluteBase = IsRegAbsolute(BaseReg.getReg());
+ bool AbsoluteIndex = IsRegAbsolute(IndexReg.getReg());
+ unsigned AddrReg = 0;
+
+ if (AbsoluteBase && AbsoluteIndex) {
+ llvm_unreachable("Unexpected absolute register pair");
+ } else if (AbsoluteBase) {
+ AddrReg = IndexReg.getReg();
+ } else if (AbsoluteIndex) {
+ assert(!BaseReg.getReg() && "Unexpected base register");
+ assert(Scale.getImm() == 1);
+ AddrReg = 0;
+ } else {
+ if (!BaseReg.getReg()) {
+ // No base, fill in relative.
+ BaseReg.setReg(FlagUseZeroBasedSandbox ? 0 : X86::R15);
+ AddrReg = IndexReg.getReg();
+ } else if (!FlagUseZeroBasedSandbox) {
+ // Switch base and index registers if index register is undefined.
+ // That is do conversions like "mov d(%r,0,0) -> mov d(%r15, %r, 1)".
+ assert (!IndexReg.getReg()
+ && "Unexpected index and base register");
+ IndexReg.setReg(BaseReg.getReg());
+ Scale.setImm(1);
+ BaseReg.setReg(X86::R15);
+ AddrReg = IndexReg.getReg();
+ } else {
+ llvm_unreachable(
+ "Unexpected index and base register");
+ }
+ }
+
+ if (AddrReg) {
+ assert(!SegmentReg.getReg() && "Unexpected segment register");
+ SegmentReg.setReg(X86::PSEUDO_NACL_SEG);
+ Modified = true;
+ }
+ }
+
+ return Modified;
+}
+
+bool X86NaClRewritePass::ApplyRewrites(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator MBBI) {
+ MachineInstr &MI = *MBBI;
+ DebugLoc DL = MI.getDebugLoc();
+ unsigned Opc = MI.getOpcode();
+
+ // These direct jumps need their opcode rewritten
+ // and variable operands removed.
+ unsigned NewOpc = 0;
+ switch (Opc) {
+ // 32-bit direct calls are handled unmodified by the assemblers
+ case X86::CALLpcrel32 : return true;
+ case X86::TAILJMPd : NewOpc = X86::JMP_4; break;
+ case X86::NACL_CG_TAILJMPd64 : NewOpc = X86::JMP_4; break;
+ case X86::NACL_CG_CALL64pcrel32: NewOpc = X86::NACL_CALL64d; break;
+ }
+ if (NewOpc) {
+ BuildMI(MBB, MBBI, DL, TII->get(NewOpc))
+ .addOperand(MI.getOperand(0));
+ MI.eraseFromParent();
+ return true;
+ }
+
+ // General Dynamic NaCl TLS model
+ // http://code.google.com/p/nativeclient/issues/detail?id=1685
+ if (Opc == X86::NACL_CG_GD_TLS_addr64) {
+
+ // Rewrite to:
+ // leaq $sym@TLSGD(%rip), %rdi
+ // call __tls_get_addr@PLT
+ BuildMI(MBB, MBBI, DL, TII->get(X86::LEA64r), X86::RDI)
+ .addReg(X86::RIP) // Base
+ .addImm(1) // Scale
+ .addReg(0) // Index
+ .addGlobalAddress(MI.getOperand(3).getGlobal(), 0,
+ MI.getOperand(3).getTargetFlags())
+ .addReg(0); // Segment
+ BuildMI(MBB, MBBI, DL, TII->get(X86::NACL_CALL64d))
+ .addExternalSymbol("__tls_get_addr", X86II::MO_PLT);
+ MI.eraseFromParent();
+ return true;
+ }
+
+ // Local Exec NaCl TLS Model
+ if (Opc == X86::NACL_CG_LE_TLS_addr64 ||
+ Opc == X86::NACL_CG_LE_TLS_addr32) {
+ unsigned CallOpc, LeaOpc, Reg;
+ // Rewrite to:
+ // call __nacl_read_tp@PLT
+ // lea $sym@flag(,%reg), %reg
+ if (Opc == X86::NACL_CG_LE_TLS_addr64) {
+ CallOpc = X86::NACL_CALL64d;
+ LeaOpc = X86::LEA64r;
+ Reg = X86::RAX;
+ } else {
+ CallOpc = X86::CALLpcrel32;
+ LeaOpc = X86::LEA32r;
+ Reg = X86::EAX;
+ }
+ BuildMI(MBB, MBBI, DL, TII->get(CallOpc))
+ .addExternalSymbol("__nacl_read_tp", X86II::MO_PLT);
+ BuildMI(MBB, MBBI, DL, TII->get(LeaOpc), Reg)
+ .addReg(0) // Base
+ .addImm(1) // Scale
+ .addReg(Reg) // Index
+ .addGlobalAddress(MI.getOperand(3).getGlobal(), 0,
+ MI.getOperand(3).getTargetFlags())
+ .addReg(0); // Segment
+ MI.eraseFromParent();
+ return true;
+ }
+
+ // Initial Exec NaCl TLS Model
+ if (Opc == X86::NACL_CG_IE_TLS_addr64 ||
+ Opc == X86::NACL_CG_IE_TLS_addr32) {
+ unsigned CallOpc, AddOpc, Base, Reg;
+ // Rewrite to:
+ // call __nacl_read_tp@PLT
+ // addq sym@flag(%base), %reg
+ if (Opc == X86::NACL_CG_IE_TLS_addr64) {
+ CallOpc = X86::NACL_CALL64d;
+ AddOpc = X86::ADD64rm;
+ Base = X86::RIP;
+ Reg = X86::RAX;
+ } else {
+ CallOpc = X86::CALLpcrel32;
+ AddOpc = X86::ADD32rm;
+ Base = MI.getOperand(3).getTargetFlags() == X86II::MO_INDNTPOFF ?
+ 0 : X86::EBX; // EBX for GOTNTPOFF.
+ Reg = X86::EAX;
+ }
+ BuildMI(MBB, MBBI, DL, TII->get(CallOpc))
+ .addExternalSymbol("__nacl_read_tp", X86II::MO_PLT);
+ BuildMI(MBB, MBBI, DL, TII->get(AddOpc), Reg)
+ .addReg(Reg)
+ .addReg(Base)
+ .addImm(1) // Scale
+ .addReg(0) // Index
+ .addGlobalAddress(MI.getOperand(3).getGlobal(), 0,
+ MI.getOperand(3).getTargetFlags())
+ .addReg(0); // Segment
+ MI.eraseFromParent();
+ return true;
+ }
+
+ return false;
+}
+
+bool X86NaClRewritePass::AlignJumpTableTargets(MachineFunction &MF) {
+ bool Modified = true;
+
+ MF.setAlignment(5); // log2, 32 = 2^5
+
+ MachineJumpTableInfo *JTI = MF.getJumpTableInfo();
+ if (JTI != NULL) {
+ const std::vector<MachineJumpTableEntry> &JT = JTI->getJumpTables();
+ for (unsigned i = 0; i < JT.size(); ++i) {
+ const std::vector<MachineBasicBlock*> &MBBs = JT[i].MBBs;
+ for (unsigned j = 0; j < MBBs.size(); ++j) {
+ MBBs[j]->setAlignment(5);
+ Modified |= true;
+ }
+ }
+ }
+ return Modified;
+}
+
+bool X86NaClRewritePass::runOnMachineFunction(MachineFunction &MF) {
+ bool Modified = false;
+
+ TM = &MF.getTarget();
+ TII = MF.getSubtarget().getInstrInfo();
+ TRI = MF.getSubtarget().getRegisterInfo();
+ Subtarget = &TM->getSubtarget<X86Subtarget>();
+ Is64Bit = Subtarget->is64Bit();
+
+ assert(Subtarget->isTargetNaCl() && "Unexpected target in NaClRewritePass!");
+
+ DEBUG(dbgs() << "*************** NaCl Rewrite Pass ***************\n");
+ for (MachineFunction::iterator MFI = MF.begin(), E = MF.end();
+ MFI != E;
+ ++MFI) {
+ Modified |= runOnMachineBasicBlock(*MFI);
+ }
+ Modified |= AlignJumpTableTargets(MF);
+ DEBUG(dbgs() << "*************** NaCl Rewrite DONE ***************\n");
+ return Modified;
+}
+
+bool X86NaClRewritePass::runOnMachineBasicBlock(MachineBasicBlock &MBB) {
+ bool Modified = false;
+ if (MBB.hasAddressTaken()) {
+ //FIXME: use a symbolic constant or get this value from some configuration
+ MBB.setAlignment(5);
+ Modified = true;
+ }
+ for (MachineBasicBlock::iterator MBBI = MBB.begin(), NextMBBI = MBBI;
+ MBBI != MBB.end(); MBBI = NextMBBI) {
+ ++NextMBBI;
+ // When one of these methods makes a change,
+ // it returns true, skipping the others.
+ if (ApplyRewrites(MBB, MBBI) ||
+ (Is64Bit && ApplyStackSFI(MBB, MBBI)) ||
+ (Is64Bit && ApplyMemorySFI(MBB, MBBI)) ||
+ (Is64Bit && ApplyFrameSFI(MBB, MBBI)) ||
+ ApplyControlSFI(MBB, MBBI)) {
+ Modified = true;
+ }
+ }
+ return Modified;
+}
+
+/// createX86NaClRewritePassPass - returns an instance of the pass.
+namespace llvm {
+ FunctionPass* createX86NaClRewritePass() {
+ return new X86NaClRewritePass();
+ }
+}
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